title: Tamm-Horsfall glycoprotein enhances PMN phagocytosis by binding to cell surface-expressed lactoferrin and cathepsin G that activates MAP kinase pathway.
abstract: The molecular basis of polymorphonuclear neutrophil (PMN) phagocytosis-enhancing activity (PEA) by human purified urinary Tamm-Horsfall glyco- protein (THP) has not been elucidated. In this study, we found human THP bound to lactoferrin (LF) and cathepsin G (CG) expressed on the surface of PMN, identified by a proteomic study with MALDI-TOF- LC/LC/mass spectrometric analysis. Pre-incubation of 10% SDS-PAGE electrophoresed PMN lysates with monoclonal anti-LF or anti-CG antibody reduced the binding with THP. To elucidate the signaling pathway of THP on PMN activation, we found THP enhanced ERK1/2 phosphorylation, reduced p38 MAP kinase phosphorylation, but had no effect on DNA binding of the five NF-kB family members in PMN. To further clarify whether the carbohydrate-side chains or protein-core structure in THP molecule is responsible for THP-PEA, THP was cleaved by different degrading enzymes with carbohydrate specificity (neuraminidase and β-galactosidase), protein specificity (V8 protease and proteinase K) or glycoconjugate specificity (carboxylpeptidase Y and O-sialoglycoprotein endopeptidase). We clearly demonstrated that the intact protein-core structure in THP molecule was more important for THP-PEA than carbohydrate-side chains. Putting these results together, we conclude that THP adheres to surface-expressed LF and CG on PMN and transduces signaling via the MAP kinase pathway to enhance PMN phagocytosis.
authors.affiliation: Institute of Molecular Medicine, National Taiwan University College of Medicine, No. 7 Chung-Shan South Road, Taipei 100, Taiwan.
authors.forename: Syue-Cian
authors.initials: SC
authors.lastname: Siao
authors.forename: Ko-Jen
authors.initials: KJ
authors.lastname: Li
authors.forename: Song-Chou
authors.initials: SC
authors.lastname: Hsieh
authors.forename: Cheng-Han
authors.initials: CH
authors.lastname: Wu
authors.forename: Ming-Chi
authors.initials: MC
authors.lastname: Lu
authors.forename: Chang-Youh
authors.initials: CY
authors.lastname: Tsai
authors.forename: Chia-Li
authors.initials: CL
authors.lastname: Yu
mesh_terms: D056649:Cathepsin G / Q000378:metabolism*; D006801:Humans; D007781:Lactoferrin / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D009504:Neutrophils / Q000276:immunology*; D010587:Phagocytosis / Q000502:physiology*; D010766:Phosphorylation; D011485:Protein Binding; D015398:Signal Transduction; D058949:Uromodulin / Q000378:metabolism / Q000502:physiology*
chemical_list: D058949:Uromodulin; D007781:Lactoferrin; D056649:Cathepsin G